xsl multiple grouping

[GMKal]

hello, I have a difficulty achieving the results I need and I hope that someone here can help me

I have an xml like this

<products>
        <Product>
                <ID>1</ID>
                <Brand>brand1</Brand>
                <Features>
                        <Feature>feature1</Feature>
                        <Feature>feature2</Feature>
                        <Feature>feature3</Feature>
                </Features>
        </Product>
        <Product>
                <ID>2</ID>
                <Brand>brand1</Brand>
                <Features>
                        <Feature>feature2</Feature>                        
                        <Feature>feature3</Feature>
                </Features>
        </Product>
        <Product>
                <ID>3</ID>
                <Brand>brand2</Brand>
                <Features>
                        <Feature>feature1</Feature>
                        <Feature>feature2</Feature>                        
                </Features>
        </Product>
</products>

I need to group the products both by brand AND feature. That means that the result should look like this:

<groups>
        <group>
                <Brand>1</Brand>
                <Feature>feature1</feature>
                <Product>1</Product>
        </group>
        <group>
                <Brand>1</Brand>
                <Feature>feature2</Feature>
                <Product>1</Product>
                <Product>2</Product>
        </group>
        <group>
                <Brand>1</Brand>
                <Feature>feature3</Feature>
                <Product>1</Product>
                <Product>2</Product>
        </group>
        <group>
                <Brand>2</Brand>
                <Feature>feature1</Feature>
                <Product>3</Product>                
        </group>
        <group>
                <Brand>2</Brand>
                <Feature>feature2</Feature>
                <Product>3</Product>                
        </group>
</groups>

Any help would be very welcome....

[jkmyoung]

Assuming brand feature is unique, Muenchian grouping:

http://www.jenitennison.com/xslt/grouping/muenchian.html

<xsl:key name="brandfeature" match="feature" use="concat(../../Brand, .)"/>

<xsl:for-each select="/products/Product/Features/Feature[count(.|key('brandfeature', concat(../../Brand, .))[1]) = 1]">
	<group>
		<Brand><xsl:value-of select="../../Brand"/></Brand>
		<Feature><xsl:value-of select="."/></Feature>
		<xsl:for-each select="key('brandfeature', concat(../../Brand, .))">
			<Product><xsl:value-of select="../../ID"/></Product>
		</xsl:for-each>
	</group>
</xsl:for-each>

[GMKal]

That worked, than you very much